sedimentation constant

sed·i·men·ta·tion con·stant

the constant s in the Svedberg equation for estimating the molecular weight of a protein from the rate of movement in a centrifugal field:where M is the molecular weight, R the gas constant, T the absolute temperature, D the diffusion constant (in square centimeters per second),  the partial specific volume of the protein, and ρ the density of the solvent. The constant s, with dimensions of time per unit of field force (s = d_rb/dt/ω²r_o where r_b is the position at time t, r₀ is the position at time 0, and ω is the angular velocity) is usually between 1 × 10^-13 and 200 × 10^-13 s. The Svedberg unit (S) is arbitrarily set at 1 × 10^-13 s and is very often used to describe the sedimentation rate of macromolecules; for example, 4S RNA.

Synonym(s): sedimentation coefficient

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sed·i·men·ta·tion con·stant

(sed'i-mĕn-tā'shŭn kon'stănt)

The constants in a Svedberg equation for estimating the molecular weight of a protein from the rate of movement in a centrifugal field. The Svedberg unit (S) is arbitrarily set at 1 × 10^-13 sec and is often used to describe the sedimentation rate of macromolecules (e.g., 4 S RNA).
Synonym(s): sedimentation coefficient.

Medical Dictionary for the Health Professions and Nursing © Farlex 2012